Social networking and the Dunbar number

The Dunbar number is a well known neurological construct that suggests our brains are only capable of maintaining good relationships with around 150 people (although it is believed to range from 100 up to 230 depending on the individual).

The relative limit for each individual is, Dunbar believed, limited by the size of their neocortex. The Dunbar number has largely passed into the mainstream heuristic when it comes to discussions around the size of social networks, and is often used in debates around the perceived value of online social networks that often number significantly higher than 150 people.

Does the number apply equally to social networks however? I mean I’m sure many of us have networks that far exceed 150, be it on Twitter or LinkedIn. Dunbar himself conducted some research into this recently and he came to the conclusion that the mental limit applies just as much online as it does offline.

The 150 limit applies to internet social networking sites just as it does in face-to-face life. Facebook’s own data shows that the average number of friends is 150-250 (within the range of variation in the face-to-face world). Remember that the 150 figure is just the average for the population as a whole. However, those who have more seem to have weaker friendships, suggesting that the amount of social capital is fixed and you can choose to spread it thickly or thinly.#

That opinion isn’t shared by researchers at Oxford University however, who found that our social networking capabilities are relatively elastic. They suggest that people with a large network of friends and strong social skills have bigger social regions of the brain than those with fewer friends.

“We’re interested in how your brain is able to allow you to navigate in complex social environments,” study researcher MaryAnn Noonan, a neuroscientist at Oxford University, said at a news conference. Basically, “how many friends can your brain handle?” Noonan said.

Of course, there is also much to support the so called weak connections within our social networks. Research last year highlighted the importance of what they termed familiar strangers. These are people we see regularly but who we don’t have any kind of relationship with, so people we see every day on the train to work for instance or at the gym.

The researchers suggest that the connections that evolve between these familiar strangers grows stronger over time. In other words, the more frequently we see that person on the train each morning, the more likely we are to become socially connected to one another.

Similarly it emerged recently that weak ties were the key to getting retweets on Twitter. It emerged that when both parties followed each other (ie a two way relationship), there was a 6% chance of either party retweeting a comment from the other. When the relationship was only one-way however, that probability rose to 9.1%, which is a boost of over 50%.

“We found that people with weak ties, such as those who only have a one-way relationship on Twitter – who don’t both follow each other – are more likely to retweet,” says Zhan Michael Shi, assistant professor in the W. P. Carey School of Business, one of the paper’s authors.

So does social media allow us to bust past the Dunbar number? I’d say the jury is still very much out.